1. Field of the Invention
The present invention relates generally to a method for the transmission of data corresponding to connections extending through a communication switching system, and in particular to a communication switching system in which data for each connection are placed in intermediary storage in data sets specific to each connection, and are redundantly transmitted to a data processing system connected to the communication switching system.
2. Description of the Prior Art
It is known in the prior art in Der Dienst bei der Deutschen Bundespost, Teilband 4, Datenvermittlungstechnik (EDS), R. V. Decker's Verlag G. Schenk, Heidelberg, Hamburg 1978, pages 232 to 242 to determine call data in a communication switching system for each of the connections going through and to place such call data in intermediate storage. These call data function, for example, to determine fees for the individual connections respectively for the detection of traffic intensity. To determine the call data in each connection set-up, a "begin set" is prepared, in which, apart from an identification of the subscriber wanting the particular connection (calling party), the dial data identifying the wanted subscriber (called party) and information regarding the time from which payment of a fee is counted as well as the type of fee accounting are stored. When disconnecting the particular call, an end set is prepared which, apart from the identification of the calling subscriber, contains data identifying the time the obligation for payment of the fee ends.
Begin and end sets are transmitted in each instance separately to an output buffer and remain there until the buffer is completely filled. Once the output buffer is filled, the begin and end sets stored in the buffer are transferred to a disk memory of the data switching system. For further processing of the begin and end sets, such call data are transmitted to a computer. For this transmission, a data transmission procedure is provided.
It is also known by Heidelberger Taschenbuecher, Datafernverarbeitung, H. Hofer, Springer-Verlag, Berlin, Heidelberg, New York 1978, pages 128 to 133 that for transmission of data blocks from a data station to an external site, the data station first supplies a request signal to the external site. The external site responds with a positive reply if it is ready to receive data. Upon receipt of this response message, the transmission of a data block takes place. Receipt of the data block is confirmed by the external site by the output of an acknowledge signal which provides information regarding the receipt of the data block.
It is an object of the present invention to provide a method to permit, with minimum control effort in the communication switching system, reliable transmission of data identifying the connections to a data processing system.